I have been listening extensively to a couple martial arts podcasts recently, and they have been very helpful and informative for me. The Applied Karate Show is hosted by Des Paroz, a very experienced and insightful karateka of the Shorinjiryu school, in Sydney, Australia. This show focuses primarily on master karate practitioners.
The second podcast is West Seattle Karate's Martial Secrets, hosted by Kris Wilder, the head instructor at this Goju-ryu karate school. This show interviews martial arts masters of all traditions, all around the world. He asks very good questions and he likes to interview people who can give a very particular insight that is different from what his previous guests could offer.
So check out a couple of these if you're interested in exploring the martial arts, its history, and what it means to practice and master the martial arts.